In the processing of foamed plastics in a two-part mold, the closed mold cavity is partly filled by means of an injection molding unit, connectable to the mold, with a predetermined amount of plastic, the remaining space being occupied by the foaming of the plastic. The air in the mold cavity escapes along with the gases freed during the foaming process through the parting line of the mold.
To be able to carry out the opening and closing movements of the two-part mold to remove the molded article, it is old to arrange one mold half stationarily on a bed plate. Into this bed plate are set two guide columns which are outside of the mold half, which extend a distance beyond the total mold height, and which are interconnected at their free ends by a tie-bar. Below the tie-bar is held a closing plate that is movable and the guide columns and that carries at its surface facing toward the bed plate the other mold half. To the tie-bar is affixed a hydraulically-actuatable piston-cylinder unit, whose piston rod engages the closing plate. By means of this piston-cylinder unit the mold can be opened and closed, so that the one mold half is lifted from the other mold half, while maintining its parallel position. If required, special interlocking contrivances may be provided at the mold halves for creating the closing force as described in the German patent application DT-AS 21 17 534.
On such a known device the movable mold half must be raised a relatively large distance from the stationary mold half to allow a satisfactory removal from the mold. This necessitates relatively long guide columns which makes such a device rather expensive. Such a device is, therefore, not economically usable for small molded articles.
For the fabrication of small moldings, such as shoe soles, out of foamed plastic a device is known in which one mold half is fixed to a stationary bed plate in a similar manner. At the bed plate is further articulated a hinged mounting plate that takes up the second mold half at its surface facing toward the bed plate. Because of this hinged mold half, the mold is easily accessible, especially for removal of the finished molded article and nevertheless has a low overall height. It is also possible here to interlock the two mold halves in closed condition by means of special contrivances. This know device has, it is true, a simple, economically-acceptable construction, but it has the drawback that it is not possible to move the two mold halves apart in parallel. Therefore, only moldings that have in the direction of the hinged mold half a level area of contact lying in the range of the parting line of the mold can be fabricated in this device.
It is, therefore, an outstanding object of the invention to provide apparatus for the processing of foamed plastic in such a way that, with the simplest and the least expensive construction, it is possible to obtain, first, a parallel opening of the two mold halves and, subsequently, a raising of one mold half on hinges.